Author: np
Date: Thu May 5 02:38:08 2011
New Revision: 221477
URL: http://svn.freebsd.org/changeset/base/221477
Log:
T4 packet timestamps.
Reference code that shows how to get a packet's timestamp out of
cxgbe(4). Disabled by default because we don't have a standard way
today to pass this information up the stack.
The timestamp is 60 bits wide and each increment represents 1 tick of
the T4's core clock. As an example, the timestamp granularity is ~4.4ns
for this card:
# sysctl dev.t4nex.0.core_clock
dev.t4nex.0.core_clock: 228125
MFC after: 1 week
Modified:
head/sys/dev/cxgbe/t4_sge.c
head/sys/modules/cxgbe/if_cxgbe/Makefile
Modified: head/sys/dev/cxgbe/t4_sge.c
==============================================================================
--- head/sys/dev/cxgbe/t4_sge.c Thu May 5 02:35:25 2011 (r221476)
+++ head/sys/dev/cxgbe/t4_sge.c Thu May 5 02:38:08 2011 (r221477)
@@ -606,6 +606,12 @@ t4_evt_rx(void *arg)
V_INGRESSQID(iq->cntxt_id) | V_SEINTARM(iq->intr_params));
}
+#ifdef T4_PKT_TIMESTAMP
+#define RX_COPY_THRESHOLD (MINCLSIZE - 8)
+#else
+#define RX_COPY_THRESHOLD MINCLSIZE
+#endif
+
void
t4_eth_rx(void *arg)
{
@@ -669,7 +675,22 @@ t4_eth_rx(void *arg)
BUS_DMASYNC_POSTREAD);
m_init(m0, NULL, 0, M_NOWAIT, MT_DATA, M_PKTHDR);
- if (len < MINCLSIZE) {
+
+#ifdef T4_PKT_TIMESTAMP
+ *mtod(m0, uint64_t *) =
+ be64toh(ctrl->u.last_flit & 0xfffffffffffffff);
+ m0->m_data += 8;
+
+ /*
+ * 60 bit timestamp value is *(uint64_t *)m0->m_pktdat. Note
+ * that it is in the leading free-space (see M_LEADINGSPACE) in
+ * the mbuf. The kernel can clobber it during a pullup,
+ * m_copymdata, etc. You need to make sure that the mbuf
+ * reaches you unmolested if you care about the timestamp.
+ */
+#endif
+
+ if (len < RX_COPY_THRESHOLD) {
/* copy data to mbuf, buffer will be recycled */
bcopy(sd->cl, mtod(m0, caddr_t), len);
m0->m_len = len;
Modified: head/sys/modules/cxgbe/if_cxgbe/Makefile
==============================================================================
--- head/sys/modules/cxgbe/if_cxgbe/Makefile Thu May 5 02:35:25 2011
(r221476)
+++ head/sys/modules/cxgbe/if_cxgbe/Makefile Thu May 5 02:38:08 2011
(r221477)
@@ -13,4 +13,7 @@ SRCS+= opt_inet.h
CFLAGS+= -I${CXGBE}
+# Provide the timestamp of a packet in its header mbuf.
+#CFLAGS+= -DT4_PKT_TIMESTAMP
+
.include <bsd.kmod.mk>
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